The Landau–Ginzburg model \(w\colon U\rightarrow \mathbb {C}\)  is obtained from this elliptic fibration \(\widetilde{w}\)  by deleting the fibre at \(\infty \)  and five horizontal sections given by the five \(\phi \) -exceptional curves. In terms of mirror symmetry, the significance of the five deleted sections is due to the fact that the anticanonical divisor \(D\subset X\)  has five corners [1]}. Changing the choice of boundary divisor by smoothing a corner of \(D\)  corresponds to extending \(w\)  along one of the missing horizontal sections, so the Landau–Ginzburg model obtained by extending \(w\)  to \(\widetilde{X}\setminus \widetilde{w}^{-1}(\infty )\)  is mirror to a del Pezzo surface of degree 5 with a smooth anticanonical divisor, as expected [2]}.
